Ab initio geometry optimization and ground state properties of layered ternary carbides Ti3MC2 (M = Al, Si and Ge)
Ab initio geometry optimization and ground state properties of layered ternary carbides Ti3MC2 (M = Al, Si and Ge)
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DOI：
10.1088/0953-8984/13/44/313
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发表时间：
2001-10
期刊：
影响因子：
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通讯作者：
Yanchun Zhou;Z. Sun;Xiaohui Wang;Shengqi Chen
中科院分区：
文献类型：
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作者：
Yanchun Zhou;Z. Sun;Xiaohui Wang;Shengqi Chen
用从头算方法对Ti_3AlC_2、Ti_3SiC_2和Ti_3GeC_2等三元层状碳化物（312相）的晶体结构进行了优化。确定了平衡晶格参数、原子在晶胞中的位置和原子间距。晶格常数的计算值与实测值之间的差异一般小于1%。从Ti_3AlC_2到Ti_3GeC_2，六方晶格的cla逐渐减小。计算的体积模量分别为190 GPa的Ti 3AlC 2，202 GPa的Ti 3SiC 2和198 GPa的Ti 3GeC 2，这是可比的TiC。电子结构表明，Ti（1，2）和C原子形成了较强的Ti（2）-C-Ti（1）-C-Ti（2）共价键链，而Ti（2）和M（M = Al，Si，Ge）之间的键合相对较弱。强的Ti（2）-C-Ti（1）-C-Ti（2）共价键链对应于高的强度和模量，而金属键对应于这些三元化合物的金属导电性。
The crystal structures of all layered ternary carbides called '312' phases including Ti3AlC2, Ti3SiC2 and Ti3GeC2 have been fully optimized by means of ab initio total-energy calculations. The equilibrium lattice parameters, the atomic positions in the unit cell and interatomic distances have been determined. The differences between the calculated and the measured lattice constants are generally less than 1%. It is also shown that cla of the hexagonal lattices decreases from Ti3AlC2 to Ti3GeC2. The calculated bulk moduli are 190 GPa for Ti3AlC2, 202 GPa for Ti3SiC2 and 198 GPa for Ti3GeC2, respectively, which are comparable to that of TiC. The electronic structures reveal that the Ti(1, 2) and C atoms form a strong Ti(2)-C-Ti(1)-C-Ti(2) covalent bond chain, while the bonding between Ti(2) and M (M = Al, Si, Ge) is relatively weak. The strong Ti(2)-C-Ti(1)-C-Ti(2) covalent bond chain corresponds to the high strength and modulus, while the metallic bond corresponds to the metallic conductivity of these ternaries.